Abstract: The ground state structure of thymine molecule was optimized using density functional method B3LYP basing on the 6-311+G basis set level. The structure, energy, and charge distribution of thymine molecule were calculated under different electric field intensities along x, y, z three directions. The results indicated that the characteristics of structure, charge distribution, energy and frontier orbital energy level difference of the thymine molecular were affected by external electric field. Furthermore, electric field strength of the influence of the molecular properties were not only determined by the electric field intensity, but also related to the direction of the electric field, which show that the response of thymine molecule to electric field was anisotropic